SmogRank / History / City race

Cities, worst air first, day by day

Each measured city's average over the 30 days to every day since January 2023, worst first. Find your own city to follow it through the race, or keep to one country.

CountriesCities
The 7 days to15 Apr 2025 That day's board

The worst cities for PM2.5 over the 7 days to 15 Apr 2025: Mae Sai 68.6 µg/m³, Delhi 62.7 µg/m³ and Chiang Khong 56.6 µg/m³.

  1. 1Mae SaiThailand68.6
  2. 2DelhiIndia62.7
  3. 3Chiang KhongThailand56.6
  4. 4Ban HouakhouaLaos56.6
  5. 5CoyhaiqueChile55.4
  6. 6Wan ChaiHong Kong52.3
  7. 7Ubon RatchathaniThailand51.9
  8. 8GuangzhouChina49.6
  9. 9AguascalientesMexico48.7
  10. 10VillarricaChile46.1
  11. 11Amnat CharoenThailand46.0
  12. 12IslamabadPakistan43.5
  13. 13MukdahanThailand43.4
  14. 14Chiang RaiThailand43.0
  15. 15YasothonThailand42.6
  16. 16Tuen MunHong Kong40.8
  17. 17NacimientoChile40.0
  18. 18KalasinThailand39.4
  19. 19Mong KokHong Kong38.9
  20. 20Victoria de DurangoMexico38.5

+ 2,874 more cities, 38.4 µg/m³ and below

Not counted on this day, too few days measured: Hanoi since 12 Apr 2025, La Unión since 12 Apr 2025, Siliguri since 11 Apr 2025 and 55 more cities.

30 days7 days
GoodModerateSensitive groupsUnhealthyVery unhealthyHazardousWHO 24-hour guideline, 15 µg/m³Fades where it stood: not counted that day

A city's number is its average over the 30 days, shown only when 21 of them were measured (5 of 7 on the 7-day race), the same minimum as the 30- and 7-day boards. A city whose monitors go quiet fades out where it stood rather than sliding down, so a gap never reads as cleaner air. Some large countries are thin or missing because their monitors' licences don't allow reuse. How we rank.

Not covered: the government monitoring networks of China and Turkey, which publish only on their own websites; we are building the readers for them. Most cities there are missing from this board, not clean. Why.